1. The Field of the Invention
The present invention is related to a nozzle plug which enhances the plume of a kinematic flare. More particularly, the present invention is related to a plug mounted at the aft end of an extendable shroud which seals the nozzle when the shroud is in a retracted position and is configured with a plume-contacting surface for enhancing the cross-sectional area of the plume when the shroud is in an extended position.
2. Technical Background
Decoy flares are used defensively by combat aircraft to evade heat-seeking missiles directed at such aircraft by an enemy. At an appropriate time after the enemy launches a heat-seeking missile, the targeted aircraft releases a decoy flare. The decoy flare burns in a manner that simulates the engines of the targeted aircraft. Ideally, the missile locks onto and pursues the decoy, permitting the targeted aircraft to escape unharmed.
Early decoy techniques utilized bundles of chaff, i.e., strips of metal which would reflect radar energy to counter radar guided missiles. The chaff bundles were housed in square or rectangular shaped cartridges which were held in correspondingly shaped dispensers on the aircraft.
As missile technology advanced, chaff bundles were accompanied by flares which produced infrared wavelength signatures greater than those produced by the engines of the target aircraft as interpreted by the heat seeking missile. Such infrared decoy flares were housed in dispensers which were previously used to carry chaff bundles. The flares are deployed by igniting an impulse cartridge which ejects the flare from the cartridge and triggers a chain of events which leads to the ignition of the flare illuminant.
Further missile technology advancements led to discriminating abilities in missiles to distinguish between the target aircraft and the decoy flare. This in turn has led to the development of kinematic, or fly-along, flares to beat or decoy the advanced discriminators found in the missiles. The kinematic flare is also deployed by igniting the impulse cartridge and ejecting the flare from its protective case.
The cases, magazines, and dispensers employed in connection with these prior technologies provide a design envelope defining the exterior dimensions of the decoy flare. Limitations on the length of new kinematic flares have been overcome by the implementation of telescoping shrouds. Such shrouds permit the flare to be stowed with the shroud in a retracted position and deploy and lock into an extended position upon firing of the flare. Increasing the effective length of the flare by the use of a telescoping shroud enables the aerodynamic characteristics of the flare to be enhanced, and allows better combustion of plume gases to occur.
The restrictions on the cross-sectional area of the flare which are imposed by the flare envelope limit the size of the plume which may be generated by the flare. Obviously, if the size of the flare's plume could be increased, the effectiveness of the flare as a decoy would be enhanced.
Safety regulations for such decoy flares require that flares satisfy "lock-set" test requirements. These requirements are designed to ensure that in the event the flare dispenser is plugged, thereby blocking physical deployment of the flare, ignition of the impulse cartridge will not trigger ignition of the flare illuminant. Generally this is accomplished by employing a safe-and-initiation device which prevents the illuminant from being ignited until the shroud is fully deployed, thereby ensuring that the flare dispenser has not been blocked prior to igniting the illuminant.
One disadvantage to the use of such safe-and-initiation devices is that they delay ignition of the illuminant until the telescoping shroud is fully deployed. Immediate ignition of the illuminant upon deployment of the flare is critical to the decoy functions of the flare. Thus, any delay between the firing of the impulse cartridge and the ignition of the illuminant is disadvantageous and should be reduced or eliminated.
From the foregoing, it will be appreciated that it would be an advancement in the art to provide a decoy flare having a plume with an enhanced cross-sectional area while preserving the physical dimensions of the flare, thereby enabling the flare to be stowed in the chaff dispensers typically found on military aircraft.
It would be a further advancement in the art to provide a flare which would satisfy lock-set test requirements while enabling immediate ignition of the illuminant upon the firing of the impulse cartridge to deploy the flare.
Such a flare is disclosed and claimed herein.